System Software

Part 1 · Two kinds of software

Software that runs the computer, and software that works for you

Before you tap any app

Turn on your phone. Before you open Messenger or GCash, a lot is already working: the lock screen, the clock, the battery and signal icons, the fingerprint or face check. You did not open any app for these. They come from the phone's operating system, a kind of system software.

Recall what software is. There are two big kinds:

System software

Programs that run and maintain the computer itself. They control the hardware and give other programs a place to run. Two main kinds: the operating system (OS) and utility programs.

Application software

Programs that do a specific job for you, the user: write a report, edit a photo, chat, pay a bill, play a game. Also called apps. (Next lesson.)

A school canteen works the same way. The picture puts the two side by side, layer by layer:

Each layer depends on the one under it. Apps run on the OS, and the OS runs the hardware. You only deal with the top layers.

Here is the difference in one table:

	System software	Application software
Job	Runs and maintains the computer	Does a task for the user
Needed?	Yes. Without an OS, the computer cannot be used.	Only the ones you need
When it runs	The OS: from the moment you turn it on. Utilities: in the background, or when needed	When you open it
Examples	Windows, Android, iOS, File Explorer, antivirus, drivers	Word, Canva, Chrome, GCash, Mobile Legends

Sort it: system or application?

Tap one answer on each card. You get the reason right away.

Android
Microsoft Word
Windows Security (antivirus)
GCash
File Explorer
Mobile Legends
A printer driver (a small program that lets the computer use a printer)
Google Chrome

0 of 8 right

Part 2 · The operating system

What an operating system does

Operating system (OS)

The main system software. It starts the computer, manages its hardware and software, and lets you interact with it. Every app needs the OS to run.

Like the canteen manager, the OS has several jobs. Here are the main ones, with the canteen job that matches:

1. Starts the computer (booting)

Loads itself into memory when you turn the computer on.

Canteen: Opens the canteen each morning

2. Gives you an interface

The screens, icons, menus, and buttons you use to talk to the computer (Part 4).

Canteen: The counter and the menu board

3. Manages programs, the CPU, and memory

Decides which program uses the CPU and gives each one a share of RAM.

Canteen: Decides who cooks what, on which stove

4. Manages files and storage

Keeps track of every file and folder: where it is saved and what it is called.

Canteen: Keeps the stock room in order

5. Manages devices

Talks to the keyboard, screen, printer, and Wi-Fi using device drivers.

Canteen: Knows how to run each machine

6. Keeps it secure

User accounts, passwords, fingerprint or face log-in, and security updates.

Canteen: Only staff in the kitchen

Device driver

A small program that tells the OS how to use one specific device, such as a printer model. Plug in a new mouse, and the OS usually finds and installs its driver by itself. This is called plug and play.

Kernel

The kernel is software, not a physical part. It is the most important part of the OS program: the core that stays in RAM the whole time the computer is on. (The rest of the OS includes the interface, settings, and file manager.) Apps never control the hardware themselves. They ask the OS, and the kernel gives the orders to the CPU, RAM, and storage.

Do not mix it up with the parts inside the CPU (such as the control unit and the arithmetic logic unit from Week 5). Those are hardware. The kernel is a program that runs on the CPU.

Function 1, step by step: booting

Booting is starting up the computer and loading the OS. Remember where programs must be for the CPU to run them: RAM, not storage . Go through the steps:

From power button to log-in screen

The top is the laptop. The green board below is what is inside it. Tap Next: the orange parts are working in that step.

1. Power on. You press the power button. Electricity reaches the parts inside, but the operating system is still sleeping on the storage drive.

Step 1 of 5

A cold boot starts from power off. A warm boot is a restart while the computer is on (for example, after an update).

Part 3 · Faster processing

How the OS makes the computer work faster

The OS has tricks that let the computer do more in the same time. Here are five, from the one you use every day to the ones you do not see:

1. Multitasking

Running more than one program at the same time. Spotify plays while you chat on Messenger and a file downloads. Today's CPUs have several cores , but you usually run more programs than there are cores. So each core takes turns between a few programs, switching so fast that they all seem to run at once. The picture shows 6 apps sharing 4 cores.

2. Multithreading

Splitting one program into smaller tasks, called threads, that run at the same time. Word checks your spelling while you keep typing. Each is a thread of the same program.

3. Multiprocessing and parallel processing

Multiprocessing: two or more CPUs or cores work at the same time, each on its own task. Parallel processing: several cores split one big task into parts, like four classmates each writing one part of a report, so it is done sooner (for example, exporting a video).

4. Memory management and virtual memory

The OS gives each open program its own part of RAM. When RAM runs out, it uses part of the storage drive as extra memory. This is virtual memory. It lets you open more programs, but it is slower.

Virtual memory is like a small study desk. When the desk is full, some books go on the floor beside you: you can still use them, but reaching them takes longer. That is why a computer with too little RAM feels slow.

5. Buffering and spooling

A buffer is a waiting area in memory for data on its way to or from a device. YouTube buffers the next seconds of a video so it plays smoothly. Spooling is buffering for a slow device such as a printer: documents wait in a print queue on the storage drive, so you can keep working while they print.

Print spooling

Tap Next and watch the print queue.

You print three files. They go into the print queue (the spool) on the storage drive in a second, so your computer is free again.

Step 1 of 4

Which trick is it?

The five are easy to mix up. Try these before you read the summary below.

You export a 10-minute video. The editing app splits it into four parts, and four CPU cores each work on one part at the same time.
In Google Docs, the text you type shows up while, at the same moment, the app saves your work.
Twenty students send files to the one printer in the lab. The files wait in line, and everyone keeps working.
Your laptop has only 4 GB of RAM. With many tabs open, it gets very slow but does not crash.

Score: 0 / 4

The five in one line each

Multitasking: many programs at once.
Multithreading: many parts of one program at once.
Multiprocessing / parallel processing: many CPUs or cores at once (on different tasks / on one big task).
Virtual memory: storage used as extra RAM.
Buffering / spooling: data waits its turn so nobody has to stop and wait.

Part 4 · Kinds of operating systems

Comparing operating systems

Operating systems differ in a few ways. These are the characteristics to compare:

Compare by	The choices
Interface	CLI (command-line interface: you type commands) or GUI (graphical user interface: icons, windows, and menus you click or tap). Phones add touch and voice.
Users at a time	Single-user (one person at a time) or multiuser (many people at once, like a school server that many students log in to at once)
Programs at a time	Single-tasking (one program at a time) or multitasking (many). Almost all of today's OSs multitask.
Where it runs	Personal (desktops, laptops), server (network), mobile (phones, tablets), or embedded (built into a device)
32-bit or 64-bit	(What is a bit ?) A 32-bit OS can use only about 4 GB of RAM. A 64-bit OS can use much more. Windows 11 is 64-bit only.
Who can change it	Proprietary (owned by a company; you cannot see or change its code: Windows, macOS, iOS) or open source (anyone can see, change, and share the code: Linux)

Two of the comparisons as pictures: how many users at a time, and who can see the code.

The same task, opening the Pictures folder, two ways. IT people still use the CLI for servers and quick fixes.

Operating systems for personal computers and servers

These are the operating systems you will meet on computers, as of 2026:

You can often tell the OS by its screen: a taskbar in the middle (Windows), a dock at the bottom (macOS), a browser front and center (ChromeOS).

OS (made by)	Used on	Good to know
Windows (Microsoft)	Most desktops and laptops	The most common PC OS. Windows 11 is current; Windows 10 support ended in October 2025.
macOS (Apple)	Mac computers only	Popular for design, video, and music work
Linux (many groups)	PCs, and most servers	Free. Comes in versions called distributions, such as Ubuntu and Linux Mint.
ChromeOS (Google)	Chromebooks	Built around the Chrome browser and cloud apps
Windows Server (Microsoft)	Servers	For company networks, accounts, and files
UNIX (Bell Labs, 1969)	Large servers and mainframes	macOS is built on it, and Linux copies its ideas

A server OS (also called a network OS) is built to serve many users over a network at the same time: sharing files, printers, websites, and accounts. Most of the web servers on the Internet run Linux.

Devices other than computers

Phones, watches, TVs, and even cars need an operating system too. A mobile OS runs phones and tablets. An embedded OS is built into a device to run just that device. Here are common examples:

If it has a screen and runs apps, or quietly runs a machine, it has an operating system inside.

Device	Operating systems
Smartphones and tablets	Android (Samsung, Xiaomi, OPPO, vivo, realme, and more), iOS and iPadOS (iPhone, iPad), HarmonyOS (Huawei)
Smartwatches	watchOS (Apple Watch), Wear OS (Google Pixel Watch, Samsung Galaxy Watch)
Smart TVs	Google TV / Android TV, Tizen (Samsung), webOS (LG)
Game consoles	Each console has its own OS (PlayStation, Xbox, Nintendo Switch)
Cars, ATMs, appliances, routers	Embedded systems, often built on Linux (for example, Android Automotive in some cars)

Look around: which OS is on your phone?

Open Settings, then About phone (Android) or General › About (iPhone). Find the OS name and version. Is it Android, iOS, or HarmonyOS? Brands also add their own look on top of Android, such as One UI (Samsung) or HyperOS (Xiaomi): the OS underneath is still Android.

Joy bought a Samsung Galaxy phone. Which operating system does it most likely run?
The registrar's office runs a server that stores every student's grades. Which OS fits that computer?
Which device does NOT need a full operating system that you install apps on?

Score: 0 / 3

Part 5 · Utility programs

Utility programs: the computer's cleaning and repair crew

Utility program

System software that maintains, protects, or speeds up the computer. Many come built into the OS; others you can download or buy. In the canteen, they are the cleaners, the pest control, and the repair crew.

The utility toolbox. Most of these come free with Windows, macOS, Android, and iOS. Open the table below to see what each one does.

Show the full table: what each utility does, and where to find it

The table lists the most common utilities and where to find them on Windows and on a phone:

Utility	What it does	On Windows	On a phone
File manager	Open, copy, move, rename, and delete files and folders	File Explorer	Files or My Files app
Search tool	Finds files, apps, and settings by name	Search box on the taskbar	Search bar on the home screen or in Settings
Disk cleanup / storage cleaner	Deletes temporary and unneeded files to free up space	Disk Cleanup, Storage Sense	Settings › Storage, or Files by Google › Clean
Disk optimizer (defragmenter)	On a hard drive: puts the scattered pieces of each file back together, so it reads faster	Defragment and Optimize Drives	Automatic
Uninstaller	Removes a program and its files completely	Settings › Apps	Hold an app › Uninstall
Backup and recovery	Makes copies of your files so you can get them back after a loss	File History, OneDrive	Google One backup, iCloud Backup
Antivirus / security	Finds and removes malware: harmful programs such as viruses	Windows Security (Microsoft Defender)	Google Play Protect
File compression	Makes files smaller (a ZIP file) to send or store	Right-click › Compress to ZIP file	Files app › Compress (on most phones)
Diagnostic tools	Checks the computer for problems and shows what slows it down	Task Manager	Battery or Device care in Settings

Careful: hard drive vs. SSD

Defragmenting helps a hard drive, whose spinning disk must move to each piece of a file. An SSD has no moving parts, so defragmenting it does not help and only wears it out. Windows knows the difference: on an SSD, "Optimize" does a different, gentler job instead.

Look around: what fills up your phone?

Open Settings › Storage (Android) or Settings › General › iPhone Storage. Which kind of file or app takes the most space? That screen is a storage utility at work.

Which utility do you need?

Your phone says "Storage full" and you cannot take more photos. Which utility helps first?
Your group's video file is 300 MB, too big to send. Which utility makes it smaller to send?
After installing a "free" game from a random website, your laptop shows pop-up ads everywhere. Which utility do you run?
Your laptop goes to the repair shop tomorrow, and the technician may erase the drive. What do you do tonight?

Score: 0 / 4

Part 6 · What comes next

The future of operating systems

Operating systems keep changing. These are the directions you can already see today:

AI built in

Assistants are becoming part of the OS itself: Copilot in Windows, Apple Intelligence on iPhones and Macs, and Gemini on Android. You ask in plain words, and the OS finds files, changes settings, or summarizes text.

More cloud

More of your files and apps live online and follow you to any device. ChromeOS was built this way. Some companies even run whole Windows computers in the cloud.

One OS, many devices

Phone, watch, laptop, TV, and car work together: a call moves from phone to laptop, a photo appears on every device. HarmonyOS was designed for this.

Stronger security

Face and fingerprint log-in, passkeys (you unlock with your fingerprint or face instead of typing a password), and automatic updates. Old versions lose updates (like Windows 10 in 2025), so users must upgrade to stay safe.

Think about it

An OS that knows everything on your phone can help you a lot. What could go wrong? Write two benefits and two risks on paper. (You will meet privacy again in the Finals.)

Part 7 · Check yourself

Self-check

Not graded. Tap an answer to see if you got it, and read why.

Which statement is correct?
What happens during booting?
You listen to Spotify while you chat on Messenger. Which OS feature makes that possible?
Your laptop has 8 GB of RAM, but your open programs need 10 GB. What does the OS use for the extra?
Which interface lets you type commands instead of clicking icons?
Which pair is correct?
Which one is a utility program?
You plug a new printer into your laptop, and Windows says "Setting up device". What is it installing?
Why should you NOT defragment an SSD?

Score: 0 / 9

Key takeaways

System software runs and maintains the computer (the OS and utility programs). Application software does a job for the user.
The OS boots the computer, gives you an interface, manages programs, memory, files, and devices, and keeps the computer secure.
To work faster, the OS uses multitasking, multithreading, multiprocessing and parallel processing, virtual memory, and buffering and spooling.
Compare OSs by interface (CLI or GUI), users, tasks, where they run, 32- or 64-bit, and proprietary or open source.
Computers: Windows, macOS, Linux, ChromeOS. Servers: Linux, Windows Server, UNIX. Phones: Android, iOS. Watches: watchOS, Wear OS.
Utility programs maintain, protect, and speed up the computer: file managers, cleanup, backup, antivirus, compression, and more.

Next lesson: Application software.

References

D. Morley and C. S. Parker, Understanding Computers: Today and Tomorrow. Course Technology, 2015, Chapter 5 (System Software: Operating Systems and Utility Programs).
M. Vermaat et al., Discovering Computers 2018: Digital Technology, Data, and Devices. Cengage Learning, 2018.
Microsoft Support pages on the end of Windows 10 support and on Optimize Drives (defragmenting and TRIM). support.microsoft.com
IT 110 Introduction to Computing Syllabus, Faculty of Computing, Engineering, and Technology, Davao Oriental State University.